LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2014 >> MX-5 Miata Sport, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System LF] >> DTC P0030
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0030

DTC P0030  A/F sensor healer control circuit problem 
DETECTION CONDITION 
  • The PCM monitors the A/F sensor impedance when under the A/F sensor heater control for 200 s.  If the impedance is more than 44 ohms  , the PCM determines that there is a A/F sensor heater control circuit problem.

Diagnostic support note 
  • This is an intermittent monitor (A/F sensor healer, HO2S heater).
  • The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle white the DTC for the same malfunction has been stored in the PCM.
  • PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
  • FREEZE FRAME DATA (Mode 2/Mode 12) is available.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • A/F sensor connector or terminals malfunction
  • A/F sensor heater malfunction
  • PCM connector or terminals malfunction
  • PCM malfunction
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA (MODE 12) AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS (A/F sensor heater, HO2S heater related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2 VERIFY RELATED SERVICE BULLETINS AVAILABILITY 
  • Verify related Service Bulletins availability.
  • Is any related Service Bulletins available?
 Yes Perform the repair or diagnosis according to the available Service Bulletins.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 VERIFY RELATED PENDING CODE AND STORED DTC 
  • Turn the ignition switch off, then to the ON position (Engine off).
  • Verify related PENDING CODE and stored DTC.
  • Are any DTCs present?
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No Go to the next step.
4 INSPECT A/F SENSOR CONNECTOR AND TERMINALS 
  • Turn the ignition switch off.
  • Disconnect the A/F sensor connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, and corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector or terminals, then go to Step 7.
No Go to the next step.
5 INSPECT A/F SENSOR HEATER 
 Yes Replace the A/F sensor, then go to Step 7.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION ).
No Go to the next step.
6 INSPECT PCM CONNECTOR AND TERMINALS 
  • Disconnect the PCM connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, and corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector or terminals, then go to the next step.
No Go to the next step.
7 VERIFY TROUBLESHOOTING OF DTC P0030 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the M-MDS.
  • Perform the KOEO or KOER self test (using M-MDS) or Drive Mode 03 (PCM Adaptive Memory Production, EGR System, A/F Sensor Heater, HO2S Heater, A/F Sensor, HO2S, and TWC Repair Verification Drive Mode) (not using M-MDS).

    (See KOEO/KOER SELF TEST ).

    (See OBD-II DRIVE MODE ).

  • Is the PENDING CODE for this DTC present?
 Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION ).
No Go to the next step.
8 VERIFY AFTER REPAIR PROCEDURE 
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No DTC troubleshooting completed.
scientia non olet · About LEMON Manuals